Various packaging techniques have been used in accordance with the features of products to prevent decomposition, denaturation, and damage while the products are sent to consumers from manufacturers. However, accidents of decomposition or denaturation of the contents in products frequently occur due to carelessness in transportation and storage. Accordingly, there is a strong need of a detection method that can monitor the storage state of products at any time during transportation and methods of non-destructively examining the states inside packages have not been well known in the art. There have been proposed a method of indirectly examining the inside states of products by measuring the surface temperature of the products using an infrared camera or using a millimeter wave, but the existing non-destructive methods have a limit that it is impossible to measure small physical/chemical/biological changes in state or a small amount of foreign substances in objects or materials because the sensitivity is very low. For example, when detecting food poisoning bacteria in food that is transported after being packed, it is impossible to a small amount of change of the bacteria directly at the sites, so those bacteria are detected on the basis of indirect indexes through a microorganism proliferation modeling by measuring temperature using infrared rays. Accordingly, there is a limit in species, amount, and accuracy of harmful bacteria and the indirect index detection method has low sensitivity, so detection is made after microorganisms have already proliferated. Therefore, it is difficult to cope with this problem in advance.
At present, a barcode is widely used as an identification factor. In general, a barcode was proposed first in ‘Calculation automation of supermarkets’ by Wallace Flint in 1932, and at present, almost all articles are printed with barcodes, and purchase and sale of products are automatically managed by a POS (Point Of Sales system). Further, the usability has been rapidly increased with IT relating to post automation, factory automation, stock management, library, document management, and medical information. Recently, with the advent of a smartphone, applications that can search prices and the lowest price of products by reading out barcodes in real time have been developed.
Barcode signals are sets of continuous black modules and white modules, in which information is encoded in accordance with the widths and rations of the modules. It is required to restore the sizes of modules with in an allowable error range in order to accurately decode information.
However, since barcode signals are sets of continuous black modules and white modules, in which information is encoded in accordance with the widths and rations of the modules, it is impossible to encode a large amount of information in a limited space and to visually check the positions, so there is a limit in applying the barcode to security, anti-forgery, and the like.